Myocardial infarction is the leading cause of papillary muscle rupture. This complication occurs in up to 5% of cases post MI and although rare, it constitutes a cardiac emergency if left untreated. On this basis, a 59-year-old male presented with low-grade fever and atypical chest pain with raised inflammatory markers and troponin levels. He was treated for infective endocarditis after echocardiography revealed a mass on the mitral valve, which was presumed to be a mitral valve vegetation and so he completed a 6-weeks course of antibiotics followed by elective mitral valve replacement surgery. During surgery, it was discovered that there was no endocarditis. Instead an unusually small muscle head of one of the posteromedial papillary muscle groups had ruptured secondary to an inferior myocardial infarction. This ruptured muscle head was highly mobile and mimicked a mitral valve vegetation. The mitral valve was successfully repaired, and the right coronary artery grafted. He made a full recovery but developed new-onset atrial fibrillation for which he is awaiting elective cardioversion. One should have a high index of suspicion for diagnosing papillary muscle rupture as it may mimic valvular vegetation on echocardiography, especially if the papillary muscle involved is an anatomical variant.
Papillary muscle involvement in acute and chronic myocardial infarction: an MRI study using multi-contrast delayed enhancement pulse sequence
